This invention relates to a method of and an apparatus for injecting a liquid, such as grease, into a boot fitted over an end portion of a shaft, such as a vehicular drive shaft to which a joint unit, such as a constant velocity joint is assembled, the boot covering the open end of the joint unit.
An apparatus has been known from the published unexamined Japanese patent application TOKKAISHO No. 61-284329 for injecting a liquid into a boot for a joint unit. The boot and the joint unit are assembled to an end portion of a driving shaft with a diametrically larger end of the boot fitted over the outer periphery of an open end of the joint unit. The shaft held in a horizontal posture is conveyed to an injection station for injecting a liquid into the boot. The injection station is provided with an opening device adapted to clamp a diametrically smaller end of the boot, which is closely fitted to the shaft, at two locations on the outer circumferential surface thereof and press the diametrically smaller end there so as to move the two locations closer to each other to enable the intermediate portion therebetween to be slackened thereby in the radially outward direction. This forms an opening between the diametrically smaller end of the boot and the shaft for the liquid injection. A nozzle adapted to be inserted into this opening.
According to the above-described method, the diametrically smaller end of a boot is clamped to form an opening for injecting a liquid therethrough. This opening cannot be formed to a large size from a viewpoint of avoiding damaging the diametrically smaller end of the boot. This makes it impossible in some cases to insert the nozzle into the opening, and easily causes an incorrect injection of a liquid into the boot.
An object of the present invention is to provide a liquid injecting method and apparatus which are capable of solving these problems and injecting a liquid into a boot reliably.